JDK14/Java14源码在线阅读
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package javax.swing.plaf;
import javax.swing.JComponent;
import javax.swing.SwingUtilities;
import javax.accessibility.Accessible;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
/**
* The base class for all UI delegate objects in the Swing pluggable
* look and feel architecture. The UI delegate object for a Swing
* component is responsible for implementing the aspects of the
* component that depend on the look and feel.
* The <code>JComponent</code> class
* invokes methods from this class in order to delegate operations
* (painting, layout calculations, etc.) that may vary depending on the
* look and feel installed. <b>Client programs should not invoke methods
* on this class directly.</b>
*
* @see javax.swing.JComponent
* @see javax.swing.UIManager
*
*/
public abstract class ComponentUI {
/**
* Sole constructor. (For invocation by subclass constructors,
* typically implicit.)
*/
public ComponentUI() {
}
/**
* Configures the specified component appropriately for the look and feel.
* This method is invoked when the <code>ComponentUI</code> instance is being installed
* as the UI delegate on the specified component. This method should
* completely configure the component for the look and feel,
* including the following:
* <ol>
* <li>Install default property values for color, fonts, borders,
* icons, opacity, etc. on the component. Whenever possible,
* property values initialized by the client program should <i>not</i>
* be overridden.
* <li>Install a <code>LayoutManager</code> on the component if necessary.
* <li>Create/add any required sub-components to the component.
* <li>Create/install event listeners on the component.
* <li>Create/install a <code>PropertyChangeListener</code> on the component in order
* to detect and respond to component property changes appropriately.
* <li>Install keyboard UI (mnemonics, traversal, etc.) on the component.
* <li>Initialize any appropriate instance data.
* </ol>
* @param c the component where this UI delegate is being installed
*
* @see #uninstallUI
* @see javax.swing.JComponent#setUI
* @see javax.swing.JComponent#updateUI
*/
public void installUI(JComponent c) {
}
/**
* Reverses configuration which was done on the specified component during
* <code>installUI</code>. This method is invoked when this
* <code>UIComponent</code> instance is being removed as the UI delegate
* for the specified component. This method should undo the
* configuration performed in <code>installUI</code>, being careful to
* leave the <code>JComponent</code> instance in a clean state (no
* extraneous listeners, look-and-feel-specific property objects, etc.).
* This should include the following:
* <ol>
* <li>Remove any UI-set borders from the component.
* <li>Remove any UI-set layout managers on the component.
* <li>Remove any UI-added sub-components from the component.
* <li>Remove any UI-added event/property listeners from the component.
* <li>Remove any UI-installed keyboard UI from the component.
* <li>Nullify any allocated instance data objects to allow for GC.
* </ol>
* @param c the component from which this UI delegate is being removed;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
*
* @see #installUI
* @see javax.swing.JComponent#updateUI
*/
public void uninstallUI(JComponent c) {
}
/**
* Paints the specified component appropriately for the look and feel.
* This method is invoked from the <code>ComponentUI.update</code> method when
* the specified component is being painted. Subclasses should override
* this method and use the specified <code>Graphics</code> object to
* render the content of the component.
*
* @param g the <code>Graphics</code> context in which to paint
* @param c the component being painted;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
*
* @see #update
*/
public void paint(Graphics g, JComponent c) {
}
/**
* Notifies this UI delegate that it is time to paint the specified
* component. This method is invoked by <code>JComponent</code>
* when the specified component is being painted.
*
* <p>By default this method fills the specified component with
* its background color if its {@code opaque} property is {@code true},
* and then immediately calls {@code paint}. In general this method need
* not be overridden by subclasses; all look-and-feel rendering code should
* reside in the {@code paint} method.
*
* @param g the <code>Graphics</code> context in which to paint
* @param c the component being painted;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
*
* @see #paint
* @see javax.swing.JComponent#paintComponent
*/
public void update(Graphics g, JComponent c) {
if (c.isOpaque()) {
g.setColor(c.getBackground());
g.fillRect(0, 0, c.getWidth(),c.getHeight());
}
paint(g, c);
}
/**
* Returns the specified component's preferred size appropriate for
* the look and feel. If <code>null</code> is returned, the preferred
* size will be calculated by the component's layout manager instead
* (this is the preferred approach for any component with a specific
* layout manager installed). The default implementation of this
* method returns <code>null</code>.
*
* @param c the component whose preferred size is being queried;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
* @return a {@code Dimension} object containing given component's preferred
* size appropriate for the look and feel
* @see javax.swing.JComponent#getPreferredSize
* @see java.awt.LayoutManager#preferredLayoutSize
*/
public Dimension getPreferredSize(JComponent c) {
return null;
}
/**
* Returns the specified component's minimum size appropriate for
* the look and feel. If <code>null</code> is returned, the minimum
* size will be calculated by the component's layout manager instead
* (this is the preferred approach for any component with a specific
* layout manager installed). The default implementation of this
* method invokes <code>getPreferredSize</code> and returns that value.
*
* @param c the component whose minimum size is being queried;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
*
* @return a <code>Dimension</code> object or <code>null</code>
*
* @see javax.swing.JComponent#getMinimumSize
* @see java.awt.LayoutManager#minimumLayoutSize
* @see #getPreferredSize
*/
public Dimension getMinimumSize(JComponent c) {
return getPreferredSize(c);
}
/**
* Returns the specified component's maximum size appropriate for
* the look and feel. If <code>null</code> is returned, the maximum
* size will be calculated by the component's layout manager instead
* (this is the preferred approach for any component with a specific
* layout manager installed). The default implementation of this
* method invokes <code>getPreferredSize</code> and returns that value.
*
* @param c the component whose maximum size is being queried;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
* @return a <code>Dimension</code> object or <code>null</code>
*
* @see javax.swing.JComponent#getMaximumSize
* @see java.awt.LayoutManager2#maximumLayoutSize
*/
public Dimension getMaximumSize(JComponent c) {
return getPreferredSize(c);
}
/**
* Returns <code>true</code> if the specified <i>x,y</i> location is
* contained within the look and feel's defined shape of the specified
* component. <code>x</code> and <code>y</code> are defined to be relative
* to the coordinate system of the specified component. Although
* a component's <code>bounds</code> is constrained to a rectangle,
* this method provides the means for defining a non-rectangular
* shape within those bounds for the purpose of hit detection.
*
* @param c the component where the <i>x,y</i> location is being queried;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
* @param x the <i>x</i> coordinate of the point
* @param y the <i>y</i> coordinate of the point
* @return {@code true} if the specified {@code x,y} location is contained
* within the look and feel's defined shape for the given component
* @see javax.swing.JComponent#contains
* @see java.awt.Component#contains
*/
@SuppressWarnings("deprecation")
public boolean contains(JComponent c, int x, int y) {
return c.inside(x, y);
}
/**
* Returns an instance of the UI delegate for the specified component.
* Each subclass must provide its own static <code>createUI</code>
* method that returns an instance of that UI delegate subclass.
* If the UI delegate subclass is stateless, it may return an instance
* that is shared by multiple components. If the UI delegate is
* stateful, then it should return a new instance per component.
* The default implementation of this method throws an error, as it
* should never be invoked.
*
* @param c a {@code JComponent} for which to create a UI delegate
* @return a {@code ComponentUI} object for {@code c}
*/
public static ComponentUI createUI(JComponent c) {
throw new Error("ComponentUI.createUI not implemented.");
}
/**
* Returns the baseline. The baseline is measured from the top of
* the component. This method is primarily meant for
* <code>LayoutManager</code>s to align components along their
* baseline. A return value less than 0 indicates this component
* does not have a reasonable baseline and that
* <code>LayoutManager</code>s should not align this component on
* its baseline.
* <p>
* This method returns -1. Subclasses that have a meaningful baseline
* should override appropriately.
*
* @param c <code>JComponent</code> baseline is being requested for
* @param width the width to get the baseline for
* @param height the height to get the baseline for
* @throws NullPointerException if <code>c</code> is <code>null</code>
* @throws IllegalArgumentException if width or height is < 0
* @return baseline or a value < 0 indicating there is no reasonable
* baseline
* @see javax.swing.JComponent#getBaseline(int,int)
* @since 1.6
*/
public int getBaseline(JComponent c, int width, int height) {
if (c == null) {
throw new NullPointerException("Component must be non-null");
}
if (width < 0 || height < 0) {
throw new IllegalArgumentException(
"Width and height must be >= 0");
}
return -1;
}
/**
* Returns an enum indicating how the baseline of the component
* changes as the size changes. This method is primarily meant for
* layout managers and GUI builders.
* <p>
* This method returns <code>BaselineResizeBehavior.OTHER</code>.
* Subclasses that support a baseline should override appropriately.
*
* @param c <code>JComponent</code> to return baseline resize behavior for
* @return an enum indicating how the baseline changes as the component
* size changes
* @throws NullPointerException if <code>c</code> is <code>null</code>
* @see javax.swing.JComponent#getBaseline(int, int)
* @since 1.6
*/
public Component.BaselineResizeBehavior getBaselineResizeBehavior(
JComponent c) {
if (c == null) {
throw new NullPointerException("Component must be non-null");
}
return Component.BaselineResizeBehavior.OTHER;
}
/**
* Returns the number of accessible children in the object. If all
* of the children of this object implement <code>Accessible</code>,
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